LEWISTON, Maine — A pair of local middle school students were sent to the hospital Wednesday after they were jumped and beaten by a larger group of youths while walking to the Lewiston High School track, police said Thursday.

By Thursday afternoon, three students had been charged in the attack. A fourth, not a student, was charged after going to Lewiston Middle School on Thursday as part of the ongoing confrontation between two groups of students.

Police said a series of fights involving students this spring culminated Wednesday afternoon when the two students were badly beaten in the area of Marcotte Park, a short distance from the school track. The victims were examined at the hospital and released, according to a source familiar with the incident.

Lewiston Deputy Police Chief James Minkowsky said his officers would increase patrols between the middle and high schools, where groups of kids hang out.

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Minkowsky confirmed that the attackers were described as Somali students.

He said there were further problems at the school Thursday, possibly stemming from the attack a day earlier. Lewiston’s School Resource Officer Corey Jacques was investigating.

One source familiar with both groups of students said those in the smaller group might have started the fight. Police said motives for the attack were not clear.

Minkowsky said all of the students involved are minors and would not be identified. More charges are likely, he said.

“It is being addressed with the typical sensitivity we apply to all minors, but handled the same way we investigate any other criminal case,” the deputy chief said. “If we discover there are overtones stemming from any other issues, this will be addressed as well.”